1. Field of the Invention
The present invention relates to a three-phase hybrid type stepping motor, and more particularly to a three-phase hybrid type stepping motor having six magnetic poles with windings and a structure capable of reducing cogging torque and magnetic distortion rate and increasing an output.
2. Description of the Prior Art
A conventionally implemented three-phase hybrid type stepping motor has twelve magnetic poles with windings as shown in FIGS. 1A, 1B and 1C or six magnetic poles with windings as shown in FIGS. 2A, 2B and 2C.
The conventionally implemented three-phase hybrid type stepping motor shown in FIGS. 1A, 1B and 1C is composed of a stator 5 having twelve magnetic poles 2 arranged on the inner periphery of an annular yoke 1 at equal intervals, windings 3 wound around the respective magnetic poles 2 to form three-phase windings and multiple small teeth 4 provided at the tip end of each magnetic pole 2, and a rotor 9 having two splitted rotor elements 7, a permanent magnet 8 held therebetween and magnetized to two polarities of N and S in an axial direction, and fifty small teeth 6 formed on an outer periphery of each of the rotor elements 7 at a regular pitch, said rotor elements 7 being shifted from each other in angular position by a xc2xd pitch of the teeth 6, the rotor 9, the rotor 9 being opposed to the stator 5 with a gap therebetween, and rotatably supported by the yoke 1.
On the contary thereto, in the three-phase hybrid type stepping motor shown in FIGS. 2A, 2B and 2C, each of the rotor elements 7 has forty small teeth 6.
Japanese Patent Application No. 240691/2000 discloses the reduction of the cogging torque and the tertiary harmonic contents in the current wave form by arranging the pole teeth provided on the tip ends of the magnetic poles with windings at the vernier pitch wherein the permeance distribution is balanced by the six order harmonic contents with respect to the three-phase hybrid type stepping motor having six magnetic poles with windings.
A still further object of the present invention is to provide a three-phase hybrid type stepping motor, wherein the three-phase windings of the stator are connected in the form of delta.
These and other objects and features of the present invention will become apparent from the following description is conjunction with the attached drawings.